PURPOSE: To perform gas purifying action by an adsorbent when the temperature in a catalyst is not high enough to be reactable, by interpositioning the absorbent in a flow path of combustion gas.

CONSTITUTION: A cylindrical combustion cylinder 1 is formed having a bottom, while its top end is opened. A flow path 1' for combustion gas is provided in the combustion cylinder 1, with a burner 2 provided to the bottom. Besides, an oxidizing catalyst 3 is provided to the top end of the combustion cylinder 1, confronting the above-mentioned burner 2, so as to cover the opening. An adsorbent 4 is provided in the combustion cylinder 1, so as to shut off the flow path 1' for combustion gas, formed in the combustion cylinder 1. The adsorbent 4 is made of alumina which is superior in heat resistant property, and it can effectively perform a purifying action (deodorizing action) when the oxidizing catalyst cannot be acted at the time immediately after ignition.